Electrical circuit control device



Feb. 17, 1942.

c. P, XENIS ET AL ELECTRICAL CIRCUIT CONTROL DEVICE Filed May 10, 1941 INSULATION THIN CONDUCT IVE IPIBB' ON INVENTORS 5 MW m m R X r A P m 5 5 N00 1% m M Patented Feb. 17, 1942 ELECTRICAL CIRCUIT CONTROL DEVICE.

Constantine P. Xenis, Little Neck, Woodman Perine, Halesite, and Robert E. King, Broklyn, N. Y., assignors to Consolidated Edison Company of New York, Inc., New York, N. Y., a corporation of New York Application May 10, 1941, Serial No. 392,910

6 Claims.

This invention relates to electrical resistancevarying devices and is particularly adaptable for potentiometers or rheostats which are intended to be adjusted by small forces, such for example as available from delicate measuring instruments.

With various types of gauges, flow meters and electrical indicating and measuring instruments, the indicating dials or pointers are ordinarily quite delicate mechanically and are moved by forces which are too small to be used to effect corresponding movements or adjustments of electrical control devices, such as rheostats or p0- tentiometers. Such resistance devices ordinarily require for their adjustment substantial mechanical forces, which also may vary considerably because of varying friction at the adjustable contact or for other reasons. The present invention, however, provides a variable resistance device which will require only a minute and substantially uniform force for its adjustment. Hence, resistance devices made according to this invention are well adapted for adjustment by small torques or other forces available from the moving parts of meters, or shafts upon which the pointers or dials of delicate instruments are mounted.

Various further and more specific objects, features and advantages of the invention will appear from the description given below taken with the accompanying drawing illustrating by way of example certain preferred forms of the invention.

The invention consists in such novel features and combinations of parts as may be shown and described in connection with the apparatus herein disclosed.

In the drawing,

Fig. 1 is a perspective view illustrating a preferred form of the invention; and

Fig. 21 is a perspective view illustrating another form of the invention.

In Fig. 1 of the drawing, a cylindrical core sulating material or composition. This member is adapted to be rotatably suspended by being cradled in loops formed of strands of suitable good conductive and flexible material as at 6 and I. The members 6 and I may for example comprise strips of thin silver ribbon embracing the lower portions of the resistance element as shown, along parallel lines at each side of a protruding circumferential flange or ridge portion 8 formed on the core member 5. The resistance element per se may comprise a winding of suitable resistance wire as at 9, such winding in the particular form shown being arranged on the core in a manner similar to the windings of ringmember is shown at 5 formed of a suitable inwound armatures. Numerous turns of the resistance winding at its midportion may be omitted if desired, as shown, since the turns at such portion would ordinarily be short circuited by the members 6 and I.

The upper ends of the strips 6 and 1 may be secured as shown to arcuately shaped insulation pieces as at In and II, as by suitable sheet metal clamping members as at ['5 and l 6. The members I0 and II in turn may be carried by a beam member 12 pivotally mounted at its center, as upon an indicator shaft I3 of a measuring instrument l4.

In case the device is to be used as a potentiometer, flexible end connections for the resistance element may be provided as at H and I 8, and in this event the adjustable center contact may comprise one or both of the ribbons 6, 1, to which electrical connection may be made through either of the clamping members l5 and I6 as shown. In case the device is to be used as a simple rheostat, one of the connections at I! or I8 may be omitted or not used.

It will be apparent that with a potentiometer or rheostat constructed and arranged as above described, the effective position of the adjustable tap or contact, along the resistance element may be varied by a very small force. That is, a small torque applied to the instrument shaft 13 will serve to tilt the beam I2, thereby pulling one end of the loop-like cradle formed by the ribbons 6 and I, upwardly as compared with the other end, and with the consequence that the resistance device will be rotated or rolled about its center of gravity, i. e., its horizontal axis. The weight of the resistance device and particularly the core member thereof, may be readily distributed symmetrically about the axis of the core member. In this connection, the weight of the winding 9 may be taken into consideration if desired, but usually the winding will be so light that its weight may be ignored in designing the resistance unit With its weight symmetrically disposed about its axis. With the weight of the resistance unit substantially symmetrically disposed about its axis, it will be apparent that upon turning the shaft E3, the effective position of the areas of contact of the members 6 and I, with the resistance winding, may be varied without raising or lowering any of the parts except as the same are substantially exactly counterbalanced, and hence without performing any substantial amount of work. That is, the two sides of the beam I2 and the parts mounted thereon, will counterbalance each otherand the resistance unit will in efiect rotate or roll without being raised or lowered, within the loop formed by the ribbons B and 1. Thus, the device may be operated by an extremely small force and the slight force which is required will be uniform to a high degree, regardless of the position of adjustment of the device in its normal use.

The ridge or flanged portion 8 surrounding the insulation core will serve to prevent the resistance unit from slipping axially out of the loops formed by the ribbons 6 and I. At the same time the turns of the resistance winding as shown may be passed through or beneath the portion 8 and are thereby held in place on the core 5. It will be understood that the exposed portions of the winding 9 around the lower peripheral portions of the device will serve to always provide an arcuate series of contact areas concentric with the axis of the core, for dependably contacting at a plurality of areas with the flexible conductive ribbons or strands 6 and I.

In case the device is to be used in power plants or other locations where the atmosphere may include coal dust, dirt or gases, which might interfere with the proper contacting of the members 6 and 1 with the resistance unit, or might tend to injure the resistance wire, then the device may be suspended in a tank as at I9 filled with a suitable insulating liquid such as a good grade of light oil.

In the form of the invention shown in Fig. 2 the resistance element may comprise for example, a ring of resistance material as at having a gap as at 21, at the ends of which flexible connections as at 22, 23 may be applied for the ends of the member 2|]. The member 20 may be formed of carbon, or of a suitable known metallic or other resistance composition and if desired, may be grooved as at 24 for receiving a suspending loop or conductive strand, such as a wire 25. The upper ends of this loop may be secured to an insulated or insulation beam 26, which in turn may be pivotally supported by being adjustably fixed on an operating shaft as at 21. In the event it is desired to use the device in portable equipment or in such a way that the resistance element may not always be suspended directly downwardly from the beam 26, then a disc-like core portion as at 28 may be secured within the member 24 and this core portion may be retained in position as upon a shaft 29 carried in any suitable bearings. However, ordinarily, unless the device is intended for portable use, the shaft 29 or its equivalent may preferably be omitted to eliminate any bearing friction involved with its use. In case a shaft or other pivoting means is used as at 29, the wire may be retained under sufiicient tension for properly engaging the resistance element, as by forming the beam 26 of resilient material.

While the invention has been described in detail with respect to particular preferred examples, it will be understood by those skilled in the art after understanding the invention, that various changes and further modifications may be made without departing from the spirit and scope of the invention, and it is intended therefore in the appended claims to cover all such changes and modifications.

What is claimed as new and desired to be secured by Letters Patent is:

1. A resistance-varying device having its weight disposed substantially symmetrically about a horizontal axis of revolution and with contact areas along an arc concentric with said axis, and adjustable contact means for said areas comprising a flexible conductor forming a loop in and by which the device is rotatably suspended.

2. In combination, a core member carrying a resistance element and having its weight disposed substantially symmetrically about a horizontal axis of revolution, contact areas for said element along an arc concentric with said axis, at the lower side of said member, and means for rotatably suspending said member and variably contacting with said areas, comprising a flexible conductor suspended between two spaced points with said member resting thereon, intermediate said points.

3. A resistance-varying device having its weight disposed substantially symmetrically about a horizontal axis of revolution and with contact areas along an arc concentric with said axis, means for suspending and rotating said device, and at the same time forming a variable contact therefor, comprising conductive ribbon, and a pivotally mounted beam to which the ends of such ribbon are attached, with the device resting on intermediate portions of the ribbon.

4. In combination, a flexible conductive loop, means constructed and arranged for movably suspending said loop whereby one end of the loop may be variably elevated as compared with the other end, and a resistance element cradled in said loop for variably contacting therewith upon such variations in elevation.

5. In combination, a flexible conductive loop, means constructed and arranged for movably suspending said loop whereby one end of the loop may be variably elevated as compared with the other end, a resistance element cradled in said loop for variably contacting therewith upon such variations in elevation, and a body of insulating liquid enveloping said element.

6. A potentiometer construction comprising, a flexible conductive loop, means constructed and arranged for movably suspending said loop whereby one end of the loop may be variably elevated as compared with the other end, and a ring-wound resistance element rotatably suspended and cradled in said loop for variably contacting therewith upon such variations in elevation.

CONSTANTINE P. XENIS.

WOODMAN PERINE. ROBERT E. KING. 

